System and Method for High Throughput Preparation of Rubber-Modified Asphalt Cement

ABSTRACT

This invention encompasses rubber modified asphalt cement compositions, as well as systems, apparatuses, methods for preparing, as well as methods for using rubber-modified asphalt cement compositions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/493,557, filed Jun. 11, 2012, which is further a continuation of U.S.patent application Ser. No. 12/733,706, filed Mar. 16, 2010, now U.S.Pat. No. 8,202,923, which is the National Stage of InternationalApplication No. PCT/US2009/005295, filed Sep. 24, 2009, which designatedthe United States and published in English, and which further claims thebenefit of priority from U.S. Provisional Application No. 61/136,677,filed Sep. 24, 2008. The foregoing related applications, in theirentirety, are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to a rubber-modified asphalt cement, and tosystems, apparatuses, and methods for preparing a rubber-modifiedasphalt cement.

BACKGROUND OF THE INVENTION

Several attempts have been made to produce rubber-modified asphaltcements having the highly desirable properties of stability andprolonged high-level resistance to water-, fuel-, and ultraviolet (UV)light-associated degradation.

Specifically, for example, U.S. Pat. No. 5,397,818, U.S. Pat. No.5,492,561 (Flanigan I) and U.S. Pat. No. 5,583,168 (Flanigan II)describe processes for liquefying rubber granules in a TRMACS process,by heating crumb rubber and asphalt to temperatures of approximately500° F. using spray jets or spray bombardment.

Although several achievements have been made in producing asphaltcements having desirable properties, a need still remain for improvedrubber-modified asphalt cement that possess superior stability andshielding properties, and for systems, apparatuses, and methods for highthroughput production of such rubber-modified asphalt cements.

The present invention provides such an improved asphalt cement, as wellas systems and methods for preparing and using such a rubber-modifiedasphalt cement.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention relates to a method for preparing arubber-modified asphalt cement composition, comprising: contactingasphalt with rubber granules to form a mixture; heating the mixture; andpassing the heated mixture through at least one high shear mixer;wherein the rubber-modified asphalt cement composition comprises anintegration value of at least 90. In another aspect, the presentinvention relates to a method for preparing a rubber-modified asphaltcement composition, comprising: contacting asphalt with rubber granulesto form a mixture; heating the mixture to a temperature of at leastabout 500° F.; and passing the heated mixture through at least one highshear mixer for greater than 30 minutes.

In another aspect, the present invention relates to a method for highthroughput preparation of a rubber-modified asphalt cement composition,comprising: contacting asphalt with at least 40,000 pounds of rubbergranules to form a mixture; heating the mixture; and passing the heatedmixture through at least one high shear mixer; wherein therubber-modified asphalt cement composition comprises an integrationvalue of at least 90, and wherein the method is performed in less than24 hours.

In another aspect, the present invention relates to a rubber-modifiedasphalt cement composition prepared by: contacting asphalt with rubbergranules to form a mixture; heating the mixture; and passing the heatedmixture through at least one high shear mixer; wherein therubber-modified asphalt cement composition comprises an integrationvalue of at least 90.

In another aspect, the present invention relates to a system forpreparing a rubber-modified asphalt cement composition, comprising: anasphalt charging device for charging asphalt into the system; a rubbercharging device for charging rubber granules into the system; at leastone heater for heating the charged asphalt, the charged rubber granules,or a mixture thereof; at least one high shear mixer for mixing thecharged asphalt and charged rubber granules into a rubber-modifiedasphalt cement composition; and a controller for controlling the asphaltcharging device, the rubber charging device, and/or the at least onehigh shear mixer, in a manner such that the rubber-modified asphaltcement composition has an integration factor of at least 90.

Several embodiments of the invention, including the above aspects of theinvention, are described in further detail as follows. Generally, eachof these embodiments can be used in various and specific combinations,and with other aspects and embodiments unless otherwise stated herein.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates an apparatus useful for preparing rubber-modifiedasphalt cement.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description, and the accompanying drawings towhich it refers, are provided describing and illustrating certainexamples or specific embodiments of the invention only and not for thepurpose of exhaustively describing all possible embodiments and examplesof the invention. Thus, this detailed description does not in any waylimit the scope of the inventions claimed in this patent application orin any patent(s) issuing form this or any related application.

To facilitate the understanding of the subject matter disclosed herein,a number of terms, abbreviations or other shorthand as used herein aredefined below. Any term, abbreviation or shorthand not defined isunderstood to have the ordinary meaning used by a skilled artisancontemporaneous with the submission of this application.

The term “asphalt” is used herein to mean any suitablenaturally-occurring asphalt or asphalt cement, syntheticallymanufactured asphalt or asphalt cement, such as any asphalt that is aby-product of a petroleum refining process, blown asphalt, blendedasphalt, residual asphalt, aged asphalt, petroleum asphalt, straight-runasphalt, thermal asphalt, paving grade-asphalt, performance gradedasphalt cement, asphalt flux, bitumen, or the like. Suitable performancegraded asphalt cements include, for example, any asphalt cements havingthe following characteristics set forth in ASTM D6373-99, the contentsof which are incorporated herein by reference:

PG64-22 PG58-28 Asphalt Cement Asphalt Cement Average 7-day max <58 <64Pavement Design Temp, ° C. Min. Pavement Design Temp, ° C. >−28 >−22Original Binder Flash Point Temp., D 92; min ° C. 230 230 Viscosity,D4402: 135 135 max. 3Pa · s Test Temp., ° C. Dynamic Shear, P 246: 58 64G°/sinδ, min. 1.00 kPa 25 mm Plate, 1 mm Gap Test Temp. at 10 rad/s, °C. Rolling Thin Film Over (Test Method D 2872) Mass Loss, max. percent1.00 1.00 Dynamic Shear, P 246: 58 64 G°/sinδ, min. 2.20 kPa 25 mmPlate, 1 mm Gap Test Temp. at 10 rad/s, ° C. Pressure Aging VesselResidue (AASHTO PP1) PAV Aging Temperature, ° C. 100 100 Dynamic Shear,P 246: 19 25 G°/sinδ, min. 5000 kPa 8 mm Plate, 2 mm Gap Test Temp. at10 rad/s, ° C. Creep Stiffness, P 245: −18 −12 S, max 300 MPa, m-value;min. 0.300 Test Temp at 60 s, ° C. Direct Tension, P 252: −18 −12Failure Strain, min. 1.0% Test Temp. at 1.0 mm/min, ° C.

Suitable asphalts also include, for example, any asphalt cements havingthe following characteristics:

Asphalt cement AC-20 AC-5 flux ASTM # Orig. visc. at 140° F. 1725 568 40ASTM D2171 in poise Penetration at 77° F. 57 153 300+ ASTM D5 100 g. 5sec. dmm Softening point ° F. 118 104 65 ASTM D36 Flash point ° F. (COC)585 588 565  ASTM D92 Ductility at 39.2° F. 0 5.5 15 ASTM D113 5 cm/min.cm

The term “rubber,” as used herein, refers to any material madesubstantially of rubber, such as, for example, virgin rubber, recycledrubber (such as from tires, inner-tubes, gaskets, rubber scrap, or thelike), peel rubber, cured rubber, and/or processed rubber of any polymertype(s), such as, for example, tire rubber (e.g., scrap tire rubber,whole tire solid rubber, and/or scrap whole tire rubber),non-solvent-treated rubber, non-pre-swelled rubber, and/or any rubberthat comprises less than about 5% (such as less than about 3% or even1%) of talc powder, such as wherein the rubber has no insolublematerials such as metals, fibers, cords, wood, rocks, dirt, and/or thelike.

The term “granules,” as used herein, refers to any suitable form ofrubber for use in preparing a rubber-modified asphalt cement, such asparticles, crumbs, and/or other particulate forms (e.g., shavings,fines, beads, or the like), which can be produced and/or processed inany manner (such as via vulcanization, ambient grinding and/or cryogenicgrinding). Moreover, granules can exist in suitable size prior toformation of the rubber-modified asphalt cement, such that, for example,greater than about 90 wt. % (such as greater than about 95 wt. %, oreven greater than about 99%) of the rubber granules, relative to thetotal weight of the rubber granules, have a size of less than about 20mesh (such as less than about 25 mesh, less than about 30 mesh, lessthan about 35 mesh, less than about 40 mesh, less than about 45 mesh,less than about 50 mesh, less than about 60 mesh, less than about 70mesh, or even less than about 80 mesh) in accordance with U.S. Sieveseries.

The term “integration” or “integration value” as used herein, refers tothe weight percent solubility of rubber-modified asphalt cement intrichloroethylene, as determined via Standard Test Method for Solubilityof Asphalt Materials in TCE-ASTM D2042. If, for example, arubber-modified asphalt cement has a solubility in trichloroethylene of98wt. %, then about 2wt. % of the total rubber introduced into theaphalt cement for integration has not successfully integrated into therubber modified asphalt cement. The terms “fully integrated” and “fullyincorporated,” as used herein, refer to a rubber-modified asphalt cementcomposition having an integration value of at least 90 (such as at least93, at least 95, at least 96, at least about 97, at least about 98, atleast about 98.2, at least about 98.4, at least about 98.6, at leastabout 98.8, at least about 99, at least about 99.2, at least about 99.4,at least about 99.6, or even at least 99.8).

Preparation of Rubber-Modified Asphalt Cement

A rubber-modified asphalt cement (RMAC) having superior properties canbe prepared in any suitable manner by mixing, blending, combining,and/or contacting asphalt and rubber granules using a system or methodthat comprises at least one high shear mixer or mill, under suitableconditions (e.g., a mixture temperature maintained at greater than about500° F.) and for a suitable duration to cause at least some (e.g., asubstantial amount or even all) of the rubber granules to be liquefiedor otherwise subsumed, incorporated, and/or integrated into the asphaltbase or medium without any significant and/or substantial degradationand/or destruction of the base asphalt occurring. In another embodiment,for example, the rubber granules and asphalt are mixed without airblowing, jet spray agitation, oxidation, and/or or substantialdistillation of the asphalt component. In some embodiments, a highthroughput system and method are provided for fast, efficient, reducedcost production of fully integrated rubber-modified asphalt cement.

In some embodiments, as illustrated in FIG. 1, asphalt is charged intoprocess vessel 102 having mixer 104 and is circulated through heatexchanger 112 through line 108 via operation of process feed pump 110.The process vessel 102 preferably has a top exit 106 for removal ofexcess gaseous hydrocarbons and other gaseous vapors, such as H₂S, whichare disposed of, for example, by incineration at a temperature of about1350° F. A portion or all of the asphalt can be recirculated throughprocess feed pump 110 via line 114 having valve 116, such as to control,adjust, and/or regulate the flow pressure of the asphalt at downstreamcomponents of the system or apparatus (e.g., heat exchanger 112 andpre-wet vessel 126).

Following passage through heat exchanger 112, some or all of the asphaltcan be routed back to process vessel 102 through line 118 having valve120, such as, to maintain the temperature of, or further heat, theasphalt (or asphalt/rubber mixture during later production stages). Theasphalt, in this manner, can be heated and maintained at any suitabletemperature (such as about 450-550° F., about 460-540° F., about480-520° F., about 490-510° F., e.g., at least about 460° F., at leastabout 480° F., at least about 490° F., at least about 500° F., or atleast about 510° F.) via circulation through heat exchanger 112, priorto being passed through the remainder of the system.

All or some of the heated asphalt is then passed through line 122(having valve 124) to pre-wet vessel 126 for mixing with rubbergranules. Rubber granules, in turn, are charged into the pre-wet vessel126 via auger 128. The asphalt and rubber granules come into contact inpre-wet vessel 126, to form a wetted asphalt/rubber mixture. Suchwetting of the rubber granules within pre-wet vessel 126 can occur inany manner. In one embodiment, the rubber granules are top loaded intopre-wet vessel 126, and a top mounted mixer within pre-wet vessel 126causes the asphalt base and rubber granules to intermix. The pre-wetvessel, in this regard, can be of any suitable size (e.g., a 1500+gallon capacity, or even a 2500+ gallon capacity), and the rubbergranules can be charged into the pre-wet vessel at any desired rate(e.g., at least 1500 pounds/hour, at least 2000 pounds/hour, at least2500 pounds/hour, or even at least 3000 pounds/hour).

The wetted asphalt/rubber mixture is pulled from pre-wet vessel 126 byprocess return pump 132 through line 130 and towards high shear mill138. A portion or all of the asphalt/rubber mixture can be recirculatedthrough process return pump 132 via line 134 having valve 136, ifdesired, in order to control, adjust, and/or regulate the flow pressureof the wetted asphalt/rubber mixture at downstream components of thesystem or apparatus (e.g., high shear mill 138).

In some embodiments, the operation of process return pump 132 andprocess feed pump 110 is synchronized in order to maintain constantliquid levels within pre-wet vessel 126.

The wetted asphalt/rubber mixture then enters high shear mixer 138,wherein the mixture is subjected to (or encounters) high shear mixingthat at least partially integrates and/or incorporates the rubbergranules into the asphalt base (thus forming a sheared, heated mixtureand/or an at least partially integrated rubber-modified asphalt cementcomposition). The high shear mixer used in the context of the presentinvention can be any suitable mixer or mill (e.g., colloid mill) capableof high shear mixing (and/or imparting mechanical shearing on) theasphalt and rubber granules components. Suitable such high shear mixersinclude, for example, any high shear mixers comprising paddles or fluidrotors, such as any Siefer high shear mixer (e.g., a Seifer SMD3 300 HPhigh shear mixer) or Silversen high shear mixer (e.g., Silversendescending head shear mixer), or any other suitable high shear mixer.The high shear mixer can comprise any suitable mill gap set, such as,for example, a mill gap set of about 0.00001-1.0 inches (such as about0.00005-0.5 inches, about 0.0001-0.1 inches, about 0.0005-0.05 inches,about 0.0005-0.01 inches, or even about 0.001-0.0075 inches).

Following passage through high shear mill 138, the at least partiallyintegrated asphalt/rubber mixture circulates or passes back to processvessel 102 through line 140, from where the mixture can be circulateagain through the system. In this manner, circulation of the heatedmixture through the system is continued, with the temperature of themixture being maintained at the desired temperature (such as about450-550° F., about 460-540° F., about 480-520° F., about 490-510° F.,e.g., at least about 460° F., at least about 480° F., at least about490° F., at least about 500° F., or at least about 510° F.), until thedesired degree of integration of the rubber granules into the asphaltmedium is achieved. Once a rubber-modified asphalt cement compositionhaving the desired integration factor is achieved, the composition ispumped out of the system into a holding vessel before being blended,oxidized, polymer modified, or shipped as is.

In operation, the asphalt component is charged to the system, is heated,and is contacted with the rubber granules component as the granules arecharged to the system. The mixture of asphalt and rubber granules can bepassed (and concurrently heated and/or maintained at a desiredtemperature) through all or some of the system during the time requiredto charge all desired asphalt and rubber components into the system. Insome embodiments, some or all of the asphalt component is heated (suchas a temperature of at least 500° F.) prior to being contacted with therubber granules component. Following charging of all asphalt and rubbergranules into the system, the heated mixture of asphalt and rubbergranules components can be passed (or continued to be passed) throughthe high shear mixer(s) for at least 30 minutes, as measured from thetime point at which all asphalt and rubber granules components have beencharged to the system and/or heated to the desired temperature. In thisregard, the asphalt and rubber granules are continued to be mixedthrough the system or method until the desired integration factor isachieved.

Any suitable duration of high shear mixing can be utilized in thepresent invention, depending on the desired finished properties of therubber-modified asphalt cement. In some embodiments, once the asphaltand rubber components are contacted within the system, the mixture ofasphalt and rubber is heated (such as to a temperature of at least about500° F.), and the heated mixture is passed and/or circulated through atleast one high shear mixer for greater than 30 minutes, greater than 45minutes, greater than 60 minutes, greater than 75 minutes, greater than90 minutes, greater than 115 minutes, or even greater than 130 minutes,as measured from the time point at which all asphalt and rubber granulescomponents have been charged to the system and/or heated to the desiredtemperature. In some embodiments, a fully integrated rubber-modifiedasphalt cement composition is prepared by passing and/or circulating aheated mixture of rubber and asphalt through at least one high shearmill for less than 240 minutes, such as less than 200 minutes, less than180 minutes, less than 160 minutes, less than 140 minutes, less than 120minutes, or even less than 90 minutes, as measured from the time pointat which all asphalt and rubber granules components have been charged tothe system and/or heated to the desired temperature. In someembodiments, a fully integrated rubber-modified asphalt cementcomposition is prepared by passing and/or circulating a heated mixtureof rubber and asphalt through at least one high shear mill for 30-240minutes (such as greater than 30 minutes and less than 240 minutes),30-200 minutes, 30-180 minutes, 30-150 minutes, 30-120 minutes, 35-240minutes, 35-210 minutes, 35-180 minutes, 35-120 minutes, 40-240 minutes,40-210 minutes, 40-180 minutes, 40-120 minutes, about 45-180 minutes,about 45-120 minutes, about 50-180 minutes about 50-120 minutes, about60-180 minutes, about 60-150 minutes about 60-120 minutes, as measuredfrom the time point at which all asphalt and rubber granules componentshave been charged to the system and/or heated to the desiredtemperature.

In some embodiments, a system and method are provided for highthroughput preparation of a fully integrated rubber-modified asphaltcement composition comprising at least 40,000 pounds (such as at least45,000 pounds, at least 50,000 pounds, at least 52,000 pounds, at least54,000 pounds, at least 56,000 pounds, at least 58,000 pounds, at least60,000 pounds, at least 62,000 pounds, at least 64,000 pounds, at least66,000 pounds, at least 68,000 pounds, at least 70,000 pounds, at least75,000, at least 80,000 pounds, at least 85,000 pounds, or at least90,000 pounds) in a period of less than 35 hours (such as less than 30hours, less than 28 hours, less than 26 hours, less than 24 hours, lessthan 22 hours, less than 20 hours, less than 18 hours, less than 16hours, less than 14 hours, or even less than 12 hours), as measured fromthe time point at which initial charging of the asphalt component beginsto the time point at which a fully integrated rubber-modified asphaltcement product comprising all charged asphalt and rubber granulecomponents is produced. In some embodiments, the high throughput systemand method comprises contacting asphalt with at least 40,000 pounds ofrubber granules, heating the mixture; and passing the heated mixturethrough at least one high shear mixer. Alternatively, or in addition,the high throughput system or method comprises contacting asphalt withat least 40,000 pounds of rubber granules to form a mixture; heating themixture to a temperature of at least about 500° F.; and passing theheated mixture through at least one high shear mixer for greater than 30minutes. Alternatively, or in addition, the high throughput system andmethod is performed using less than 1.2 million pounds (such as lessthan 1.0 million pounds; less than 800,000 pounds; less than 600,000pounds; less than 400,000 pounds; less than 300,000 pounds; less than200,000 pounds; less than 150,000 pounds; less than 125,000 pounds; oreven less than 100,000 pounds) of asphalt. 100311 In one exampleembodiment, 156,000 pounds of asphalt and 26 super sacks (eachcontaining 2000 pounds) were charged into a system comprising a singlehigh shear mixer, the tire rubber being charged at a rate of 45minutes/super sack. During the time required to charge all of theasphalt and tire rubber components, the already-charged portions ofthese asphalt and tire rubber components were mixed, heated to 500° F.,and circulated through the system. Once charging of the asphalt and tirerubber components into the system was complete, and the complete mixturewas heated to the desired temperature, the heated mixture of asphalt andtire rubber was passed (or continued to be passed) through the highshear mixer and the remainder of the system for two hours. From thisprocess, a rubber-modified asphalt cement composition comprising anintegration value of at least 98 was produced.

The rubber-modified asphalt cement composition can comprise any desiredamount of rubber. For example, the RMAC can comprise greater than about5 wt. %, such as greater than about 8 wt. %, about 10 wt. %, about 12wt. %, or even greater than about 14 wt. % of rubber, relative to thetotal weight of the RMAC, and/or have a rubber content in the range ofabout 5-15 wt. %, such as about 6-14 wt. %, about 7-13 wt. %, about7.5-12.5 wt. %, about 8-12 wt. %, about 8.5-12.5 wt. %, or even about9-11 wt. %, relative to the total weight of the RMAC, as well compriseone or more (including all) of the properties described in this sectionof the application (for example, rubber content, flash point, softeningpoint, penetration, and/or solubility). In another embodiment, the RMACcan be more concentrated, i.e., having one or more properties (forexample, rubber content, flash point, softening point, penetration,and/or solubility) different and/or higher than those desired for thesubsequent pre-treatment and/or emulsification steps. For example, theRMAC can comprise greater than about 16 wt. %, about 18 wt. %, about 20wt. %, about 25 wt. %, about 30 wt. %, or even greater than about 35 wt.% of rubber (relative to the total weight of the RMAC), and/or have arubber content in the range of about 16-35 wt. %, about 18-30 wt. %,about 20-35 wt. %, or about 20-30 wt. %, relative to the total weight ofthe RMAC. In this regard, in the event that the RMAC has one or moreproperties (for example, rubber content, flash point, softening point,penetration, and/or solubility) that are higher than the desiredproperties for the subsequent pre-treatment and/or emulsification steps,the RMAC can be modified prior to these subsequent steps, such as byblending the RMAC with asphalt. In one embodiment, for example, a RMACconcentrate having greater than about 30 wt. % of rubber, relative tothe total weight of the RMAC, is blended (prior to the pre-treatment andemulsification steps) with additional asphalt in a manner such that theRMAC comprises about 5-15 wt. % of rubber, relative to the total weightof the RMAC, as well as one or more (including all) of the propertiesdescribed in this section of the application (for example, rubbercontent, flash point, softening point, penetration, and/or solubility).

In one embodiment, the rubber within the RMAC has an average size ofless than about 20 microns, such as less than about 18 microns, about 16microns, about 14 microns, about 12 microns, about 11 microns, about 10microns, about 9 microns, about 8 microns, about 7 microns, about 6microns, about 5 microns, about 4 microns, about 3 microns, about 2microns, about 1 micron, about 0.75 micron, about 0.5 micron, or evenless than about 0.1 micron. In another embodiment, greater than about 1%(such as greater than about 3%, about 5%, about 10%, about 15%, or evengreater than about 10% by weight) of the rubber in the RMAC has anaverage size of about 0.1-20 (such as about 1-15, about 5-15, about5-20, about 10-20, or even about 10-15) microns, with the remainder ofthe rubber having an average particle size of less than about 10 (suchas less than about 8, about 6, or even less than about 4) microns. Inanother embodiment, the RMAC comprises less than about 8 wt. % (such asless than about 6 wt. %, less than about 5 wt. %, less than about 4 wt.%, less than about 3 wt. %, less than about 2 wt. %, less than about 1wt. %, less than about 0.5 wt. %, less than about 0.25 wt. %,substantially no, or even no) rubber that is in a solid state.

In one embodiment, the RMAC exhibits a solubility in trichloroethylene(as determined via ASTM D2042) of at least about 90% (such as at leastabout 92%, at least about 94%, at least about 95%, at least about 96%,at least about 97%, at least about 98%, at least about 98.2%, at leastabout 98.4%, at least about 98.6%, at least about 98.8%, at least about99%, at least about 99.2%, at least about 99.4%, at least about 99.6%,or even at least 99.8%). For example, it is preferred, in oneembodiment, that when about 3 grams of the RMAC is dissolved in about100 mL of trichloroethylene and filtered through a 150 mm No. 52 filterpaper, less than about 10 wt. % (such as less than about 8 wt. %, about6 wt. %, about 5 wt. %, about 4 wt. %, about 3 wt. %, about 2 wt. %,about 1.8 wt. %, about 1.6 wt. %, about 1.4 wt. %, about 1.2 wt. %,about 1 wt. %, about 0.8 wt. %, about 0.6 wt. %, about 0.4 wt. %, oreven less than about 0.2 wt. %) of the RMAC remains on the filter paperfollowing such filtering.

Alternatively, or in addition, the RMAC exhibits a softening point (asdetermined via ASTM D36) greater than about 90° F., such as greater thanabout 100° F., or even greater than about 110° F. - - - a point atwhich, for example, a weight (such as a steel ball having a diameter ofabout 9.5 mm and a mass of about 3.50±0.05 g) penetrates or settles atleast about 1 inch into a sample of the RMAC, using a ring and ballsoftening point apparatus. In one preferred embodiment, the RMAC has asoftening point of about 115-125° F.

Alternatively, or in addition, the RMAC comprises a penetration at 77°F. (as determined via ASTM D5) of less than about 60 dmm, such as lessthan about 50 dmm, about 40 dmm, about 30 dmm, about 20 dmm, or evenless than about 10 dmm (such as about 5-50 dmm, about 10-40 dmm, about15-35 dmm, or even about 15-30 dmm), at which, for example, a 1mm-diameter needle penetrates into the RMAC at a needle load of about100 grams for a duration of about 5 seconds.

Alternatively, or in addition, the RMAC comprises a flash point (asdetermined via ASTM D 93) of at least about 460° F., such as at leastabout 480° F., at least about 500° F., at least about 510° F., at leastabout 520° F., at least about 530° F., at least about 540° F., or evenat least about 550° F.

In one embodiment, the RMAC is an asphalt cement concentrate having thefollowing properties:

Content Derived from Recycled Tire Rubber = 18-25% Solubility inTrichloroethylene (ASTM D2042) = 97.5% (min) Penetration @ 25° C. (ASTMD 5) = 60-90 dmm Absolute Viscosity @ 60° C. (ASTM D2171) = 1000-1600Flash Point - Cleveland Open Cup 450 F. (min) (ASTM D 92) = SofteningPoint (ASTM D36) = 110-120 F.

In one embodiment, the RMAC comprises about 9-13 wt. % of rubber(relative to the total weight of the RMAC), a penetration at 77° F. (asdetermined via American Society for Testing and Materials (ASTM) D5) ofabout 18-22 dmm, a softening point (as determined via ASTM D36) greaterthan about 112° F., and a solubility in trichloroethylene (as determinedvia ASTM D2042) of at least about 98%.

In some embodiments, in addition to the rubber and asphalt components,other additives that enhance, cause, and/or assist in devulcanization,liquefaction, and/or break-down of the rubber are combined, mixed,contacted, and/or blended with the rubber and/or asphalt componentsprior to and/or during contact of the rubber granules and asphalt inpreparing the RMAC. For example, such other additives can aid inincorporation and/or combination of the rubber into the asphaltcomponent, and/or to adjust or alter the physical properties (e.g.,softening point, hardness, stability) of the RMAC. For example, anyanti-foam agents, polymer latex, and/or sulfonic acids (e.g., DBSAand/or p-TSA) can be used in preparing the RMAC, such as described inU.S. Pat. No. 5,496,400 (Doyle), U.S. Pat. No. 7,087,665 (Sylvester),U.S. Pat. App. No. 2005/0131113, filed Feb. 7, 2005 (Sylvester), and/orU.S. Pat. App. No. 2007/2049762, filed Jul. 10, 2006 (Sylvester). Insome preferred embodiments, however, no such other additives are used inpreparing the RMAC.

In another embodiment, a system is provided for preparing the RMAC thatcomprises an asphalt charging device for charging asphalt into thesystem; a rubber charging device for charging rubber granules into thesystem; at least one heater for heating the charged asphalt, the chargedrubber granules, or a mixture thereof; at least one high shear mixer formixing the charged asphalt and charged rubber granules into arubber-modified asphalt cement composition (i.e., for preparing the RMACfrom the heated mixture of charged asphalt and charged rubber granulescomponents); and a controller for controlling the asphalt chargingdevice, the rubber charging device, and/or the at least one high shearmixer, in a manner such that the rubber-modified asphalt cementcomposition has any desired integration factor. Additionally, as isdiscussed herein, as is illustrated in FIG. 1, and as would beappreciated by those of skill in the art, the system may furthercomprise any additional components (such as lines, valves, inputconduits, output conduit, recycle loops, etc.) needed and/or desired tooptimize production of the RMAC and/or to enhance the effectiveness,efficiency, speed, and/or other desirable properties achievable throughuse of the system. In those embodiments in which the system comprisestwo or more (e.g., three or more, four or more, or even five or more)high shear mixers, such mixers can be arranged in any desired manner,such as in series, in parallel, or both. It should be noted that thesystem depicted in FIG. 1 is provided for illustration purposes only,and is in no way intended to be limiting.

The controller used in the present invention can be any controller thatis suitable for controlling, coordinating, manipulating, and/oroptimizing the operation of one or more components of the system (suchas, for example, the asphalt charging device, the rubber chargingdevice, and/or the at least one high shear mixer of the presentinvention) in a manner such that a rubber-modified asphalt compositionhaving any desired integration factor is produced. In some embodiments,the controller is a semi-automatic controller that allows that anydesired degree of user input and/or control during the operation of thesystem. In some embodiments, the controller is an automatic controller.

The systems and methods described herein are low energy, energyefficient, and low cost systems and methods for the production ofrubber-modified asphalt cement compositions, as compared to conventionalsystems and methods not comprising one or more high shear mixers incombination with the other discussed factors. In particular, forexample, use of the present low energy system and/or method to produce arubber modified asphalt cement composition from 52,000 pounds of rubbergranules and having an integration factor of 98, would require at least5% (such as at least 10%, at least 15%, at least 20%, at least 25%, oreven at least 40%) less energy, as compared to the energy required by aconventional system to produce a rubber-modified asphalt cementcomposition from 52,000 pounds of rubber granules and having anintegration factor of 95.

Other End Products

The RMAC can be used alone, or in combination with any other components,to form any desired emulsions, slurry seals, surface sealers, bindercompositions, and/or other desired end products for use in any desiredapplication. In one embodiment, for example, a composition comprisingthe RMAC can be applied to any paved surface, such as any roadway,driving surface, and/or paved surface (such as to form a seal-coatand/or surface sealer) in any suitable manner (such as by computer ratecontrol asphalt spreader truckers, hand spray wands, and/or bysqueegees) to form a cured coating. Additionally, a compositioncomprised the RMAC can be applied to any industrial surface (such as toenhance corrosion resistance of steel, concrete, or the like, and/or toimprove fire resistance of such surfaces), any building surface such asany roof surface (such as to form a seal-coat and/or surface sealer forthe surface, such as proximate to any asphalt roof surface such asasphalt roof shingles), and/or the like, in any suitable manner. Inother embodiments, the composition comprising the RMAC can be form anysuitable industrial coating composition, surface sealer composition,roof sealer composition, and/or roofing asphalt cement, or the like. Inall of these embodiments, the composition comprising the RMAC can form acured coating when applied to the target surface.

Such end products comprising the RMAC can be prepared in any suitablemanner by combining, mixing, contacting, and/or blending any desiredamount of the RMAC with any corresponding amount of other component(s)(e.g., emulsification solution) to produce a composition having anydesired properties (such as high and/or enhanced resistance to water,fuel, and/or UV and/or no tackiness, low tackiness, and/or substantiallyno tackiness properties), as taught, for example, in U.S. ProvisionalPat. App. 61/071,473, filed Apr. 30, 2008, the contents of which areincorporated in their entirety herein.

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

It will be apparent to one of ordinary skill in the art that manychanges and modification can be made to the disclosures presented hereinwithout departing from the spirit or scope of the appended claims.

What is claimed is:
 1. A method for preparing a rubber-modified asphaltcement composition, comprising: contacting asphalt with rubber granulesto form a mixture; heating the mixture; and passing the heated mixturethrough at least one high shear mixer; wherein the rubber-modifiedasphalt cement composition comprises an integration value of at least90.
 2. The method of claim 1, wherein the heating step comprises heatingthe mixture to a temperature of at least about 500° F.
 3. The method ofclaim 1, wherein the passing step comprises passing the heated mixturethrough the at least one high shear mixer for greater than 30 minutes.4. A method for preparing a rubber-modified asphalt cement composition,comprising: contacting asphalt with rubber granules to form a mixture;heating the mixture to a temperature of at least about 500° F.; andpassing the heated mixture through at least one high shear mixer forgreater than 30 minutes.
 5. The method of claim 5, wherein therubber-modified asphalt cement composition comprises an integrationvalue of at least
 95. 6. A method for high throughput preparation of arubber-modified asphalt cement composition, comprising: contactingasphalt with at least 40,000 pounds of rubber granules to form amixture; heating the mixture; and passing the heated mixture through atleast one high shear mixer; wherein the rubber-modified asphalt cementcomposition comprises an integration value of at least 95, and whereinthe method is performed in less than 24 hours.
 7. The method of claim 6,wherein the rubber-modified asphalt cement composition comprising about65-95 wt. % of asphalt and about 5-35 wt. % of rubber granules.
 8. Themethod of claim 6, wherein the heating step comprises heating themixture to a temperature of at least about 500° F.
 9. The method ofclaim 6, wherein the passing step comprises passing the heated mixturethrough the at least one high shear mixer for greater than 30 minutes.10. A rubber-modified asphalt cement composition prepared by: contactingasphalt with rubber granules to form a mixture; heating the mixture; andpassing the heated mixture through at least one high shear mixer;wherein the rubber-modified asphalt cement composition comprises anintegration value of at least
 95. 11. The composition of claim 10,wherein the mixture is heated to a temperature greater than 500° F. 12.The composition of claim 10, wherein the heated mixture is passedthrough the at least one high shear mixer for greater than 30 minutes.13. The composition of claim 10, wherein the rubber-modified asphaltcement composition comprises about 65-95 wt. % of asphalt and about 5-35wt. % of rubber granules.
 14. A system for preparing a rubber-modifiedasphalt cement composition, comprising: an asphalt charging device forcharging asphalt into the system; a rubber charging device for chargingrubber granules into the system; at least one heater for heating thecharged asphalt, the charged rubber granules, or a mixture thereof; atleast one high shear mixer for mixing the charged asphalt and chargedrubber granules into a rubber-modified asphalt cement composition; and acontroller for controlling the asphalt charging device, the rubbercharging device, and/or the at least one high shear mixer, in a mannersuch that the rubber-modified asphalt cement composition has anintegration factor of at least
 95. 15. The system of claim 14, whereinthe system is capable of high throughput production in less than 24hours of a rubber-modified asphalt cement composition comprising atleast 40,000 pounds of rubber granules, wherein the composition has anintegration value of at least
 95. 16. The system of claim 14, whereinthe controller is a semi-automatic controller.
 17. The system of claim14, wherein the controller is an automatic controller.